Such a heat exchanger arrangement is known from EP 0 916 908 B1. The pot-like heat exchanger housing of this heat exchanger arrangement comprises an outer housing part with an outer circumferential wall and with an outer bottom wall as well as an inner housing part with an inner circumferential wall and with an inner bottom wall. Connecting branches, via which heat carrier medium to be sent into the heat carrier medium flow space, i.e., for example, water, can be fed and removed from the heat carrier medium flow space, are provided on the outer housing part. A ring-like outer circumferential wall section, which is to be connected, on the one hand, to the outer circumferential wall of the outer housing part for enclosing the heat carrier medium flow space in a fluid-tight manner, is integrally connected to the inner circumferential wall of the inner housing part. On the other hand, this outer circumferential wall section defines, together with the inner circumferential wall, a ring-like area of the heat carrier medium flow space, through which passes a waste gas flow connecting piece leading into an interior space of the housing arrangement.
A fuel-operated vehicle heater of such a design can be used, for example, as a vehicle heating system as is shown in FIG. 1 of DE 10 2006 012 212 A1. It is possible in this vehicle heating system to send the medium to be heated, here the cooling liquid in the coolant system of an internal combustion engine via different flow paths in a temperature-dependent and pressure-dependent manner. A flow connection, which can be released or blocked by a valve arrangement operating in both a pressure-dependent manner and a temperature-dependent manner, is created for this between an inlet leading to the heat carrier medium flow space of a heat exchanger arrangement and an outlet leading away from the heat carrier medium flow space. It is possible in this manner to send the heat carrier medium, for example, only through a vehicle heat exchanger for heating the air to be introduced into the interior space of the vehicle but not through the internal combustion engine, or to also send it additionally through the internal combustion engine or only through the vehicle heat exchanger and the internal combustion engine, but essentially not through the heat exchanger arrangement.